The Onkalo spent nuclear fuel repository is a

deep geological repository A deep geological repository is a way of storing hazardous or radioactive waste within a stable geologic environment (typically 200–1000 m deep). It entails a combination of waste form, waste package, engineered seals and geology that is suite ...

for the final disposal of

spent nuclear fuel Spent nuclear fuel, occasionally called used nuclear fuel, is nuclear fuel that has been irradiated in a nuclear reactor (usually at a nuclear power plant). It is no longer useful in sustaining a nuclear reaction in an ordinary thermal reactor an ...

. It is near the Olkiluoto Nuclear Power Plant in the municipality of

Eurajoki Eurajoki ( sv, Euraåminne) is a municipality of Finland located in the region of Satakunta in the province of Western Finland. The municipality has a population of () and covers an area of of which is water. The population density is . The m ...

, on the west coast of

Finland Finland ( fi, Suomi ; sv, Finland ), officially the Republic of Finland (; ), is a Nordic country in Northern Europe. It shares land borders with Sweden to the northwest, Norway to the north, and Russia to the east, with the Gulf of B ...

. It is being constructed by

Posiva Posiva Oy is a Finnish company with headquarters in the municipality of Eurajoki, Finland. It was founded in 1995 by Teollisuuden Voima (60% of stock) and Fortum (40% of stock), two Finnish nuclear plant operators, for researching and creating a m ...

, and is based on the KBS-3 method of nuclear waste burial developed in

Sweden Sweden, formally the Kingdom of Sweden,The United Nations Group of Experts on Geographical Names states that the country's formal name is the Kingdom of SwedenUNGEGN World Geographical Names, Sweden./ref> is a Nordic country located on ...

by Svensk Kärnbränslehantering AB (SKB). The facility is expected to be operational in 2023.

History

After the Finnish Nuclear Energy Act was amended in 1994 to specify that all

nuclear waste Radioactive waste is a type of hazardous waste that contains radioactive material. Radioactive waste is a result of many activities, including nuclear medicine, nuclear research, nuclear power generation, rare-earth mining, and nuclear weapons r ...

produced in Finland must be disposed of in Finland, Olkiluoto was selected in 2000 as the site for a long-term underground storage facility for Finland's spent nuclear fuel. The facility, named "Onkalo" (meaning "small cave" or "cavity") is being built in the

granite Granite () is a coarse-grained (phaneritic) intrusive igneous rock composed mostly of quartz, alkali feldspar, and plagioclase. It forms from magma with a high content of silica and alkali metal oxides that slowly cools and solidifies undergro ...

bedrock In geology, bedrock is solid Rock (geology), rock that lies under loose material (regolith) within the crust (geology), crust of Earth or another terrestrial planet. Definition Bedrock is the solid rock that underlies looser surface mater ...

at the Olkiluoto site, about five kilometers from the power plants. The municipality of Eurajoki issued a building permit for the facility in August 2003 and excavation began in 2004. The site was selected after a long process, which started in 1983 with a screening of the whole Finnish territory. From 1993 until 2000, four prospective sites were examined: Romuvaara in

Kuhmo Kuhmo (known as ''Kuhmoniemi'' until 1937) is a town and a municipality in Finland and is located at the south-eastern corner of the Kainuu region. The municipality has a population of () and covers an area of of which is water. The population ...

, Kivetty in

Äänekoski Äänekoski () is a town in Finland. It is located in the Central Finland region, about north of Jyväskylä. The town has a population of () and covers an area of of which is water. The population density is . Neighbouring municipalities ...

, Olkiluoto in

and Hästholmen in

Loviisa Loviisa (; sv, Lovisa ; formerly Degerby) is a municipality and town of inhabitants () on the southern coast of Finland. It is located from Helsinki and from Porvoo. About 43 per cent of the population is Swedish-speaking. The municipality co ...

. Besides geological and environmental considerations, the opinions of local residents were also taken into account. Eurajoki and Loviisa were singled out for being the locations with the highest local support. The former also had more favorable geographic conditions, thus in 1999 Posiva proposed it to the Finnish government as the selected location. The municipality of Eurajoki confirmed its approval of the site, and the national government ratified the decision in May 2001. Posiva started construction of the site in 2004. The Finnish government issued the company a licence for constructing the final disposal facility on 12 November 2015. Posiva expects operations to begin in 2023.

Construction

The facility was constructed by and will be operated by

, a company owned by the two existing producers of nuclear power in Finland,

Fortum Fortum Oyj is a Finnish state-owned energy company located in Espoo, Finland. In addition to Finland, it focuses on Germany and other countries in Central Europe, Great Britain, Russia and the Nordic region. Fortum operates power plants, inc ...

and

TVO TVO (stylized as tvo), formerly known as TVOntario, is a publicly funded English-language educational television network and media organization serving the Canadian province of Ontario. It operates flagship station CICA-DT (channel 19) in To ...

. (

Fennovoima Fennovoima Ltd ( fi, Fennovoima Oy) is a nuclear power company established by Russian state's nuclear company Rosatom and a consortium of Finnish state-owned power and industrial companies. The company does not own any nuclear capacities; however ...

, a company which was planning its first nuclear reactor, is not a stockholder of Posiva.) The facility's constructions plans are divided into four phases: * Phase 1 (2004–09) focused on excavation of the large access tunnel to the facility, spiraling downward to a depth of . * Phase 2 (2009–11) continued the excavation to a final depth of . The characteristics of the bedrock were studied in order to adapt the layout of the repository. ** In 2012, Posiva submitted an application for a license to construct the repository. The license was granted in November 2015. * Phase 3 (2015–17) construction of the repository * Phase 4, the encapsulation and burial of areas filled with spent fuel, is projected to begin around 2023. Once in operation, the disposal process will involve placing twelve fuel assemblies into a

boron steel Boron steel refers to steel alloyed with a small amount of boron, usually less than 1%. The addition of boron to steel greatly increases the hardenability of the resulting alloy. Description Boron is added to steel as ferroboron (~12-24% B). As ...

canister and enclosing it in a copper capsule. Each capsule will then be placed in its own hole in the repository and overpacked with

bentonite clay Bentonite () is an absorbent swelling clay consisting mostly of montmorillonite (a type of smectite) which can either be Na-montmorillonite or Ca-montmorillonite. Na-montmorillonite has a considerably greater swelling capacity than Ca-mon ...

. The estimated cost of this project is about €818 million, which includes construction, encapsulation, and operating costs. The State Nuclear Waste Management Fund has approximately €1.4 billion from charges for generated electricity. The Onkalo repository is expected to be large enough to accept canisters of spent fuel for around one hundred years. At this point, the final encapsulation and burial will take place, and the access tunnel will be backfilled and sealed.

Criticism

In 2012, a research group at the Royal Institute of Technology in Stockholm, Sweden, published research that suggests that the copper capsules are not as corrosion-proof as the companies planning the repositories claim (see KBS-3). These claims were later refuted when SKB undertook follow-up studies, which indicated that the alleged corrosion process does not exist, and that the initial experiments were not correctly executed and/or the wrong conclusions were drawn. In 2019, another study concluded that radiation effects should not significantly damage the canisters after 100,000 years.

Treatment in media

Danish director Michael Madsen has co-written and directed a feature-length documentary '' Into Eternity'' (2010) where the initial phase of the excavation is featured and experts interviewed. The director's special emphasis is on the

semantic Semantics (from grc, σημαντικός ''sēmantikós'', "significant") is the study of reference, meaning, or truth. The term can be used to refer to subfields of several distinct disciplines, including philosophy, linguistics and comput ...

difficulties in meaningfully marking the depository as dangerous for people in the distant future. American anthropologist Vincent Ialenti has written a book
Deep Time Reckoning
' (MIT Press, 2020) that explores how Onkalo repository "safety case" experts envisioned distant future ecosystems and reflected on the limits of human knowledge. His book is based on 32-months of in-person fieldwork in Finland.

References

External links